NICHOLAS STADDON is the director of new plants for Monrovia, a Southern California nursery that earned the EPA Evergreen Award for its pollution-prevention efforts.

"If you've never tried a kumquat, you're in for a treat. The fruits have a sweet rind, but the orange flesh is tart—a delicious contrast in flavors. Eat them right from the garden, toss them in a salad, or make marmalade. A kumquat tree is compact and easy to grow. If you live in a warmer climate, it can reach eight feet. In colder regions, plant it in a container that can be brought indoors and situate it in a sunny spot. The tree will stay dwarf and perfume your home with a heavenly fragrance when in bloom, then get loaded with bright-orange fruit that's stunning against its dark-green foliage. Plant kumquat trees—whether indoors or out—in well-draining soil and water them weekly (more in very hot weather), making sure they get full to partial sun."